The present invention relates to an ink-jet recording head, in which a piezoelectric element is formed via a vibration plate in a portion of a pressure generating chamber communicating with a nozzle orifice that ejects ink droplets, and ink droplets are ejected by displacement of the piezoelectric element, and to a manufacturing method of the same and an ink-jet recording apparatus.
With regard to the ink-jet recording head, in which a portion of a pressure generating chamber communicating with a nozzle orifice that ejects ink droplets is constituted of a vibration plate, and the vibration plate is deformed by a piezoelectric element to pressurize ink in the pressure generating chamber, thus ink droplets are ejected from the nozzle orifice, there are two types of recording heads put into practical use: one using a piezoelectric actuator of longitudinal vibration mode with a piezoelectric element expanding and contracting in the axis direction; and the other using a piezoelectric actuator of flexural vibration mode.
The former can change the volume of the pressure generating chamber by abutting an end surface of the piezoelectric element against the vibration plate, and manufacturing of a head suitable to high density printing is enabled. On the contrary, a difficult process, in which the piezoelectric element is cut and divided into a comb teeth shape to make it coincide with an array pitch of the nozzle orifices, and the operation of positioning and fixing the cut and divided piezoelectric element onto the pressure generating chamber are required, thus there is the problem of a complicated manufacturing process.
On the other hand, in the latter, the piezoelectric element can be fabricated and installed on the vibration plate by a relatively simple process, in which a green sheet as a piezoelectric material is adhered while fitting a shape thereof to the shape of the pressure generating chamber and is sintered. However, a certain size of vibration plate is required due to the usage of flexural vibration, thus there is the problem that a high density array of the piezoelectric elements is difficult.
Meanwhile, in order to solve such a disadvantage of the latter recording head, as shown in Japanese Patent Laid-Open No. Hei 5 (1993)-286131, a recording head is proposed, in which an even piezoelectric material layer is formed over the entire surface of the vibration plate by film deposition technology, the piezoelectric material layer is cut and divided into a shape corresponding to the pressure generating chamber by a lithography method, and the piezoelectric element is formed so as to be independent for each pressure generating chamber.
According to this, the operation of adhering the piezoelectric element onto the vibration plate is not required, and thus there is the advantage that not only the piezoelectric element can be fabricated and installed by accurate and simple means, that is, the lithography method, but also the thickness of the piezoelectric element can be thinned and a high-speed drive thereof is enabled.
Moreover, in such an ink-jet printing head, since the pressure generating chamber is formed so as to penetrate in the thickness direction of the head by performing etching to a plate from the surface opposite that having the piezoelectric element made thereon, a pressure generating chamber having a high dimensional accuracy can be arranged relatively easily with high density.
However, in such an ink-jet recording head, when a relatively large plate having a diameter of, for example, about 6 to 12 inches is to be used as the plate forming the pressure generating chamber, the thickness of the plate cannot help being thickened due to the problem of handling and the like, and accompanied with this, the depth of the pressure generating chamber is deepened. For this reason, if the thickness of a compartment wall partitioning the pressure generating chambers is not thickened, a sufficient rigidity is not obtained, thus there are problems that cross talk occurs, a desired ejection characteristic is not obtained, and so on. If the thickness of the compartment wall is thickened, nozzles cannot be arrayed in a high array density, thus there is the problem that printing quality with high resolution cannot be achieved.
On the other hand, in the piezoelectric actuator of the longitudinal vibration mode, a structure is conceived, in which the wide width portion is provided on the vibration plate side of the pressure generating chamber, the width of portions other than the wide width portion of the pressure generating chamber is reduced, and the thickness of the compartment walls is increased. In this case, however, an operation such as processing and pasting for the wide width portion of the pressure generating chamber is required, thus causing problems on operationality and accuracy.
In consideration of the foregoing circumstances, the object of the present invention is to provide an ink-jet recording head, in which the rigidity of the compartment wall is improved, the pressure generating chambers can be arranged in a high density, and cross talk between each pressure generating chamber is reduced, and to provide a manufacturing method of the same and an ink-jet recording apparatus.
A first aspect of the present invention for solving the above-described problems is an ink-jet recording head, which comprises: a passage-forming substrate having a silicon layer consisting of single crystal silicon, in which a pressure generating chamber communicating with a nozzle orifice is defined; and a piezoelectric element for generating a pressure change in the pressure generating chamber, the piezoelectric element being provided on a region facing the pressure generating chamber via a vibration plate constituting a part of the pressure generating chamber, characterized in that the pressure generating chamber is formed so as to open to one surface of the passage-forming substrate and not to penetrate there through, at least one bottom surface of the inner surfaces of the pressure generating chamber, the bottom surface facing to the one surface, is constituted of an etching stop surface as a surface in which anisotropic etching stops, and the piezoelectric element is provided on the one surface side of the passage-forming substrate by a film formed by film deposition technology and a lithography method.
In the first aspect, since the pressure generating chamber is formed without penetrating through the passage-forming substrate, the rigidity of the compartment wall partitioning the pressure generating chamber is maintained, crosstalk is restrained, and the ink-jet recording head having nozzle orifices in a high density can be mass-manufactured relatively readily.
A second aspect of the ink-jet recording head of the present invention according to the first aspect is characterized in that a piezoelectric layer constituting a part of the piezoelectric element has crystal subjected to priority orientation.
In the second aspect, crystal is subjected to priority orientation as a result of depositing the piezoelectric layer in a thin film step.
A third aspect of the ink-jet recording head of the present invention according to the second aspect is characterized in that the piezoelectric layer has crystal formed in a columnar shape.
In the third aspect, crystal is formed in a columnar shape as a result of depositing the piezoelectric layer in the thin film step.
A fourth aspect of the ink-jet recording head of the present invention according to any one of the first to third aspects is characterized in that the passage-forming substrate consists only of the silicon layer.
In the fourth aspect, the pressure generating chamber is defined only with the silicon layer.
A fifth aspect of the ink-jet recording head of the present invention according to the fourth aspect is characterized in that the passage-forming substrate consists of single crystal silicon of plane orientation (110), and the plane (110) formed by half etching which becomes the etching stop surface.
In the fifth aspect, the (110) plane of the passage-forming substrate becomes the bottom surface of the pressure generating chamber, and the pressure generating chamber is formed without penetrating through the passage-forming substrate.
A sixth aspect of the ink-jet recording head of the present invention according to the fourth aspect is characterized in that the passage-forming substrate consists of single crystal silicon of plane orientation (100), and the (111) plane becomes the etching stop surface.
In the sixth aspect, the (111) plane becomes the substantial bottom surface of the pressure generating chamber, and thus the pressure generating chamber is formed without penetrating through the passage-forming substrate.
A seventh aspect of the ink-jet recording head of the present invention according to the sixth aspect is characterized in that a cross section of the pressure generating chamber has an approximately triangular shape.
In the seventh aspect, since the rigidity of the compartment wall among the pressure generating chambers is significantly increased, the pressure generating chambers can be arranged in a high density, and crosstalk can be prevented.
An eighth aspect of the ink-jet recording head of the present invention according to any one of the sixth and seventh aspects is characterized in that, in the region of the vibration plate, which faces each of the pressure generating chambers, a protruding portion protruding toward the pressure generating chamber side is formed across a longitudinal direction.
In the eighth aspect, the protruding portion is formed in the vibration plate as a result of forming the pressure generating chamber by anisotropic etching.
A ninth aspect of the ink-jet recording head of the present invention according to any one of the sixth and seventh aspects is characterized in that a first film including an inner surface of the vibration plate constituting a part of the pressure generating chamber and a second film formed on the first film are provided, an etching hole for supplying an etching liquid to a surface of the one surface side of the passage-forming substrate in forming the pressure generating chamber is formed in the first film, and the etching hole is closed by the second film.
In the ninth aspect, since the pressure generating chamber is formed by etching the passage-forming substrate by an etching liquid supplied from the etching hole provided in the first film, the pressure generating chamber can be formed relatively readily with good accuracy. In addition, the etching hole can be closed readily and surely by the second film constituting the vibration plate.
A tenth aspect of the ink-jet recording head of the present invention according to the ninth aspect is characterized in that the etching hole is formed in the region facing the pressure generating chamber.
In the tenth aspect, the etching liquid is surely supplied to the surface of the passage-forming substrate via the etching hole.
An eleventh aspect of the ink-jet recording head of the present invention according to any one of the eighth to tenth aspects is characterized in that a protective layer having an opening portion in the region facing the pressure generating chamber is provided on the passage-forming substrate, and the pressure generating chamber is formed by etching the passage-forming substrate via the opening portion of the protective layer.
In the eleventh aspect, the pressure generating chamber can be formed with relatively good accuracy by etching the passage-forming substrate via the opening portion of the protective layer.
A twelfth aspect of the ink-jet recording head of the present invention according to the eleventh aspect is characterized in that the protective layer is a polycrystal silicon layer having boron diffused therein.
In the twelfth aspect, the protective layer that will be a mask in forming the pressure generating chamber by etching can be formed relatively readily.
A thirteenth aspect of the ink-jet recording head of the present invention according to any one of the eleventh and twelfth aspects is characterized in that the etching hole is provided outside of the region facing the pressure generating chamber, and a space portion communicating with this etching hole is defined between the first film and the protective film.
In the thirteenth aspect, the pressure generating chamber is formed by etching the passage-forming substrate from the etching hole via the space portion.
A fourteenth aspect of the ink-jet recording head of the present invention according to any one of the ninth to thirteenth aspects is characterized in that the pressure generating chamber is formed in an elongate shape, and the etching hole consists of a slit formed along the longitudinal direction of the pressure generating chamber.
In the fourteenth aspect, since the etching hole consists of a slit, the passage-forming substrate can be surely etched via the etching hole, and thus the pressure generating chamber can be formed readily with good accuracy.
A fifteenth aspect of the ink-jet recording head of the present invention according to any one of the ninth to thirteenth aspects is characterized in that the etching hole consists of a plurality of pores provided at a specified interval.
In the fifteenth aspect, since the etching hole consists of pores provided in a plurality of spots, the passage-forming substrate can be surely etched via the etching hole.
A sixteenth aspect of the ink-jet recording head of the present invention according to any one of the ninth to fifteenth aspects is characterized in that a lower electrode film constituting the piezoelectric element is formed on the second film, and the piezoelectric layer constituting the piezoelectric element is formed on the lower electrode film.
In the sixteenth aspect, since the lower electrode film is formed on the second film, the strength of the vibration plate is increased.
A seventeenth aspect of the ink-jet recording head of the present invention according to any one of the ninth to fifteenth aspects is characterized in that the second film constitutes the lower electrode film constituting the piezoelectric element, and the piezoelectric layer constituting the piezoelectric element is directly formed on the second film.
In the seventeenth aspect, since the lower electrode film doubles as the second film constituting the vibration plate, the manufacturing process can be simplified.
An eighteenth aspect of the ink-jet recording head of the present invention according to any one of the ninth to seventeenth aspects is characterized in that the first film is any one of a silicon oxide film, a silicon nitride film and a zirconium oxide film.
In the eighteenth aspect, the first film having a superior etching resistance can be formed relatively readily.
A nineteenth aspect of the ink-jet recording head of the present invention according to any one of the ninth to eighteenth aspects is characterized in that the second film is any one of a silicon oxide film, a silicon nitride film and a zirconium oxide film, alternatively a laminated film obtained by laminating any of the films.
In the nineteenth aspect, the second film constituting a part of the vibration plate can be readily formed. In addition, the strength of the vibration plate can be adjusted by forming the second film as a laminated film.
A twentieth aspect of the ink-jet recording head of the present invention according to any one of the ninth to nineteenth aspects is characterized in that the inner surface of the vibration plate forming a part of the inner wall surfaces of the pressure generating chamber forms a convex shape toward the direction of the piezoelectric element, and the vibration plate forms a convex shape toward the direction of the piezoelectric element so as to correspond to the convex shape of the inner surface of the vibration plate.
In the twentieth aspect, the pressure generating chamber can be formed relatively readily with good accuracy.
A twenty-first aspect of the ink-jet recording head of the present invention according to any one of the first to third aspects is characterized in that the passage-forming substrate has an insulation layer and passage layers, any one of which is a silicon layer, on both surfaces of said insulation layer, and a surface of the insulating layer becomes the etching stop surface.
In the twenty-first aspect, when the pressure generating chamber is formed in the silicon layer by etching, etching stops readily and surely by the insulating layer. In addition, since the thickness of the passage-forming substrate is thickened, handling thereof is facilitated.
A twenty-second aspect of the ink-jet recording head of the present invention according to any one of the first to twenty-first aspects is characterized in that a reservoir supplying ink to the pressure generating chamber is formed in the other surface side of the passage-forming substrate.
In the twenty-second aspect, since the reservoir having a volume sufficiently large for the volume of the pressure generating chamber is provided, pressure change in the reservoir is absorbed by ink itself therein.
A twenty-third aspect of the ink-jet recording head of the present invention according to the twenty-second aspect is characterized in that the reservoir directly communicates with the pressure generating chamber.
In the twenty-third aspect, ink is directly supplied from the reservoir to each pressure generating chamber.
A twenty-fourth aspect of the ink-jet recording head of the present invention according to the twenty-second aspect is characterized in that an ink communicating passage communicating with one end portion in the longitudinal direction of the pressure generating chamber is formed on one surface side of the passage-forming substrate, and the reservoir is made to communicate with the ink communicating passage.
In the twenty-fourth aspect, since ink is supplied from the reservoir via the ink communicating passage to each pressure generating chamber, even if a sectional area of communicating portion between the reservoir and the ink communicating passage varies, resistance of ink can be controlled with a narrowed portion, and variety in the ink ejection characteristics among the pressure generating chambers can be reduced.
A twenty-fifth aspect of the ink-jet recording head of the present invention according to the twenty-fourth aspect is characterized in that the ink communicating passage is provided for each of the pressure generating chambers.
In the twenty-fifth aspect, ink is supplied from the reservoir to each pressure generating chamber via the ink communicating passage provided for each pressure generating chamber.
A twenty-sixth aspect of the ink-jet recording head of the present invention according to the twenty-fourth aspect is characterized in that the ink communicating passage is continuously provided across the direction where the pressure generating chambers are parallelly provided.
In the twenty-sixth aspect, ink is supplied from the reservoir via a common ink communicating passage to each pressure generating chamber.
A twenty-seventh aspect of the ink-jet recording head of the present invention according to any one of the twenty-second to twenty sixth aspects is characterized in that the pressure generating chambers are parallelly provided along the longitudinal direction thereof, and the reservoir is provided between the pressure generating chambers parallelly provided along the longitudinal direction, and communicates with the pressure generating chambers at both sides.
In the twenty-seventh aspect, since the pressure generating chambers communicating with the reservoir are parallelly provided at both sides of the reservoir, arrangement of the ink supply passages and the pressure generating chambers in a higher density is achieved.
A twenty-eighth aspect of the ink-jet recording head of the present invention according to any one of the first to twenty-first aspects is characterized in that the pressure generating chambers are formed on both surfaces of the passage-forming substrate.
In the twenty-eighth aspect, since the pressure generating chambers can be arranged in a high density without damaging the rigidity of the compartment wall of the pressure generating chamber, it is possible to highly densify the heads.
A twenty-ninth aspect of the ink-jet recording head of the present invention according to any one of the first to twenty-eighth aspects is characterized in that the film constituting the piezoelectric element is provided on the pressure generating chamber and is a film formed on a sacrificial layer finally removed.
In the twenty-ninth aspect, the piezoelectric element can be readily formed in the region facing the pressure generating chamber in a thin film process by filling the pressure generating chamber with the sacrificial layer.
A thirtieth aspect of the ink-jet recording head of the present invention according to any one of the first to twenty-ninth aspects is characterized in that the depth of the pressure generating chamber ranges between 20 xcexcm and 100 xcexcm.
In the thirtieth aspect, the rigidity of the compartment wall is maintained by forming the pressure generating chamber so as to have a specified width.
A thirty-first aspect of the ink-jet recording head of the present invention according to any one of the first to thirtieth aspects is characterized in that a nozzle communicating passage allowing the pressure generating chamber and the nozzle orifice to communicate with each other is provided.
In the thirty-first aspect, ink is ejected from the pressure generating chamber via the nozzle communicating passage and the nozzle orifice.
A thirty-second aspect of the ink-jet recording head of the present invention according to the thirty-first aspect is characterized in that the nozzle communicating passage is provided in one end portion side in the longitudinal direction of the pressure generating chamber, which is opposite to that having the reservoir.
In the thirty-second aspect, ink is stably supplied from the reservoir to the pressure generating chamber, and ink is favorably ejected from the nozzle orifice.
A thirty-third aspect of the ink-jet recording head of the present invention according to any one of the nineteenth and twentieth aspects is characterized in that the nozzle communicating passage is formed by removing the vibration plate.
In the thirty-third aspect, the nozzle communicating passage can be formed readily.
A thirty-fourth aspect of the ink-jet recording head of the present invention according to the thirty-third aspect is characterized in that an inner surface of the nozzle communicating passage is covered with adhesive.
In the thirty-fourth aspect, exfoliation of the vibration plate due to ink passing through the nozzle communicating passage is prevented.
A thirty-fifth aspect of the ink-jet recording head of the present invention according to any one of the twenty-first to thirty-fourth aspects is characterized in that the passage-forming substrate consists of an SOI substrate having silicon layers on both surfaces of the insulating layer, the pressure generating chamber is formed on one of the silicon layers constituting the SOI substrate, and the surface of the insulting layer becomes the etching stop surface.
In the thirty-fifth aspect, when the pressure generating chamber is formed in the silicon layer by etching, etching stops readily and surely by the insulating layer.
A thirty-sixth aspect of the ink-jet recording head of the present invention according to the thirty-fifth aspect is characterized in that each of the silicon layers constituting the SOI substrate has a thickness different from that of the other, and the one silicon layer having the pressure generating chambers formed thereon is thinner than the other silicon layer.
In the thirty-sixth aspect, the pressure generating chamber is formed relatively shallowly, the rigidity of the compartment wall partitioning the pressure generating chambers is increased, and crosstalk is restrained.
A thirty-seventh aspect of the ink-jet recording head of the present invention according to any one of the thirty-fifth and thirty-sixth aspects is characterized in that the nozzle communicating passage allowing the pressure generating chamber and the nozzle orifice to communicate with each other is formed in one of the silicon layers constituting the SOI substrate.
In the thirty-seventh aspect, since the nozzle communicating passage is formed in the same layer as that having the pressure generating chamber, the head can be miniaturized.
A thirty-eighth aspect of the ink-jet recording head of the present invention according to any one of the thirty-fifth and thirty-sixth aspects is characterized in that the nozzle communicating passage allowing the pressure generating chamber and the nozzle orifice to communicate with each other penetrates the insulating layer constituting the SOI substrate and is formed on the other silicon layer, and the nozzle orifice is provided on the surface side of the other silicon layer.
In the thirty-eighth aspect, the ink-jet recording head of a type having the nozzle orifice on the surface of the passage-forming substrate, which is opposite to that having the piezoelectric element, is realized.
A thirty-ninth aspect of the ink-jet recording head of the present invention according to the thirty-seventh aspect is characterized in that a sealing plate having a space for sealing the piezoelectric element inside thereof is joined onto the vibration plate, and the nozzle orifice is formed on the sealing plate.
In the thirty-ninth aspect, the ink-jet recording head of a type having the nozzle orifice at the piezoelectric element side of the passage-forming substrate is realized. In addition, one substrate can combine a sealing function and a nozzle function.
A fortieth aspect of the ink-jet recording head of the present invention according to the thirty-seventh aspect is characterized in that the nozzle communicating passage is extended from the end portion in the longitudinal direction of the pressure generating chamber, and the nozzle orifice is provided at the end surface side of the passage-forming substrate.
In the fortieth aspect, the ink-jet recording head of a type having the nozzle orifice at the end surface side of the passage-forming substrate.
A forty-first aspect of the ink-jet recording head of the present invention according to the fortieth aspect is characterized in that the nozzle communicating passage is extended to the end surface of the passage-forming substrate, and a nozzle plate having the nozzle orifice is joined to the end surface of the passage-forming substrate.
In the forty-first aspect, the nozzle orifice can be formed relatively readily at the end surface side of the passage-forming substrate.
A forty-second aspect of the ink-jet recording head of the present invention according to the fortieth aspect is characterized in that the nozzle orifice is formed on an end portion of the nozzle communicating passage by removing a portion in the height direction of the silicon layer.
In the forty-second aspect, the nozzle orifice can be formed relatively readily in the passage-forming substrate together with the pressure generating chamber.
A forty-third aspect of the ink-jet recording head of the present invention according to any one of the thirty-ninth to forty-second aspects is characterized in that an IC is integrally formed in the sealing plate.
In the forty-third aspect, the IC is integrally formed in the sealing plate joined to the passage-forming substrate, thus the manufacturing process can be simplified, and the number of parts can be reduced, leading to cost reduction.
A forty-fourth aspect of the ink-jet recording head of the present invention according to any one of the twenty-first to forty-third aspects is characterized in that the plane orientation of the silicon layer is a (001) plane.
In the forty-fourth aspect, the reservoir and the like can be formed with high accuracy also by wet etching.
A forty-fifth aspect of the ink-jet recording head of the present invention according to the forty-fourth aspect is characterized in that the longitudinal direction of the pressure generating chamber is a  less than 110 greater than  direction.
In the forty-fifth aspect, the pressure generating chambers can be formed with good accuracy and high density.
A forty-sixth aspect of the ink-jet recording head of the present invention according to any one of the twenty-first to forty-third aspects is characterized in that the main plane of the silicon layer where the pressure generating chamber is formed has a (110) orientation, and the longitudinal direction of the pressure generating chamber is a  less than 1-12 greater than  direction.
In the forty-sixth aspect, the pressure generating chambers can be formed with good accuracy and high density.
A forty-seventh aspect of the present invention is an ink-jet recording apparatus characterized by comprising the ink-jet recording head according to any one of the first to forty-sixth aspects.
In the forty-seventh aspect, an ink-jet recording apparatus can be realized, in which the ink ejection performance of the heads is improved and the heads are highly densified.
A forty-eighth aspect of the present invention is a method of manufacturing an ink-jet recording head, in which a piezoelectric element allowing a pressure generating chamber to generate a pressure change via a vibration plate is formed in a region facing the pressure generating chamber formed in a passage-forming substrate, the method of manufacturing an ink-jet recording head characterized by comprising the steps for: forming the pressure generating chamber on a passage-forming substrate having at least a silicon layer consisting of single crystal silicon without penetrating in the height direction of the passage-forming substrate; filling the pressure generating chamber with a sacrificial layer; forming the vibration plate on the sacrificial layer side of the passage-forming substrate and forming the piezoelectric element in the region facing the pressure generating chamber; and removing the sacrificial layer filled in the pressure generating chamber.
In the forty-eighth aspect, the pressure generating chamber can be formed relatively readily without penetrating the passage-forming substrate.
A forty-ninth aspect of the method of manufacturing the ink-jet recording head of the present invention according to the forty-eighth aspect is characterized in that the passage-forming substrate consists of an SOI substrate having silicon layers consisting of single crystal silicon on both surfaces of an insulating layer, and in the step where a pressure generating chamber is formed, one of the silicon layers of the SOI substrate is patterned to form the pressure generating chamber.
In the forty-ninth aspect, the pressure generating chamber can be formed relatively readily without penetrating the passage-forming substrate.
A fiftieth aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the forty-eighth and forty-ninth aspects is characterized in that, during the step where a pressure generating chamber is formed, a nozzle communicating passage communicating with the nozzle orifice from an end portion in the longitudinal direction of the pressure generating chamber is formed.
In the fiftieth aspect, the pressure generating chamber and the nozzle communicating passage can be simultaneously formed in the passage-forming substrate.
A fifty-first aspect of the method of manufacturing the ink-jet recording head of the present invention according to the fiftieth aspect is characterized in that an ink communicating passage allowing one side surface of the silicon layer and the pressure generating chamber to communicate with each other is formed, and in the step of removing a sacrificial layer, the sacrificial layer is removed by wet etching via the ink communicating passage.
In the fifty-first aspect, the sacrificial layer can be removed relatively readily and surely by performing wet etching via the ink communicating passage.
A fifty-second aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the forty-eighth to fiftieth aspects is characterized in that the step of removing the sacrificial layer is performed by etching via an opening portion penetrating the vibration plate to expose the sacrificial layer.
In the fifty-second aspect, the sacrificial layer can be removed relatively readily and surely by etching via the opening portion.
A fifty-third aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the forty-eighth to fifty-second aspects is characterized in that the step of filling with a sacrificial layer includes: the step of forming the sacrificial layer so as to have at least a thickness approximately equal to the depth of the pressure generating chamber in a region corresponding to the pressure generating chamber of the passage-forming substrate; and the step of removing a sacrificial layer other than that of the pressure generating chamber by polishing.
In the fifty-third aspect, the pressure generating chamber can be filled with the sacrificial layer readily and surely.
A fifty-fourth aspect of the method of manufacturing an ink-jet recording head of the present invention according to the fifty-third aspect is characterized in that the sacrificial layer is formed by a jet molding method.
In the fifty-fourth aspect, the sacrificial layer can be partially formed, and the pressure generating chamber can be filled with the sacrificial layer relatively readily.
A fifty-fifth aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the forty-eighth to fifty-fourth aspects is characterized in that the sacrificial layer is selected from a group consisting of phosphorous-doped silicate glass (PSG), boron phosphorous-doped silicate glass (BPSG), silicon oxide (SiOx) and silicon nitride (SiNx).
In the fifty-fifth aspect, the sacrificial layer can be removed readily and surely by using a specified material therefor.
A fifty-sixth aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the forty-eighth to fifty-fifth aspects is characterized in that the insulating layer is formed as the vibration plate, and a lower electrode layer, a piezoelectric layer and an upper electrode layer are sequentially formed in a laminated state on the insulating layer and patterned to form the piezoelectric element.
In the fifty-sixth aspect, the piezoelectric element of a flexural vibration mode can be formed relatively readily.
A fifty-seventh aspect of the method of manufacturing the ink-jet recording head of the present invention according to the fifty-sixth aspect is characterized in that the vibration plate doubles as the lower electrode layer.
In the fifty-seventh aspect, the structure of the head can be simplified, and the number of manufacturing steps can be reduced.
A fifty-eighth aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the forty-eighth to fifty-seventh aspects is characterized in that the pressure generating chamber and an ink passage are formed by anisotropic etching.
In the fifty-eighth aspect, the pressure generating chambers can be formed with good accuracy and high density.
A fifty-ninth aspect of the present invention is a method of manufacturing an ink-jet recording head, which comprises: a passage-forming substrate consisting of a single crystal silicon substrate, in which a pressure generating chamber communicating with a nozzle orifice ejecting ink is defined; and a piezoelectric element consisting of a lower electrode film, a piezoelectric layer and an upper electrode film, the piezoelectric element being provided on one surface of the passage-forming substrate via a vibration plate, the method of manufacturing an ink-jet recording head characterized by comprising the steps of: forming a region that will be a space portion between the vibration plate and the passage-forming substrate on a side of the passage-forming substrate where the vibration plate is formed; forming the vibration plate on a surface of the passage-forming substrate; laminating sequentially the lower electrode film, the piezoelectric layer and the upper electrode film on the vibration plate and patterning the same to form the piezoelectric element; and forming the pressure generating chamber by performing anisotropic etching for the passage-forming substrate from the piezoelectric element side via the space portion.
In the fifty-ninth aspect, the pressure generating chambers can be formed relatively readily with good accuracy and high density.
A sixtieth aspect of the method of manufacturing the ink-jet recording head of the present invention according to the fifty-ninth aspect is characterized in that the step of forming a space portion includes: a first depositing step of forming a polycrystal silicon film on one surface of the passage-forming substrate; and a boron diffusing step of diffusing highly concentrated boron in a region of the polycrystal silicon film, which excludes the region corresponding to the pressure generating chamber portion in the passage-forming substrate, and the step for forming a pressure generating chamber includes: a hole forming step for removing the other part of the region of the vibration plate, the region corresponding to the pressure generating chamber portion in the passage-forming substrate, to form an etching hole; and the step of removing a portion of the polycrystal silicon film where boron is not diffused and one side surface portion of the passage-forming substrate under the portion by anisotropic wet etching from the etching hole.
In the sixtieth aspect, since a portion of the polycrystal silicon film, which has boron diffused therein, is not removed by anisotropic wet etching, a pressure generating chamber of a specified shape can be formed readily with good accuracy.
A sixty-first aspect of the method of manufacturing the ink-jet recording head of the present invention according to the sixtieth aspect is characterized in that the boron diffusing step diffuses boron so that an element containing density thereof can be 1xc3x971020 number/cm3 or more.
In the sixty-first aspect, a specified amount of boron is diffused, thus etching surely stops by this portion where boron is diffused when the polycrystal silicon film is removed by etching.
A sixty-second aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the sixtieth and sixty-first aspects is characterized in that the boron diffusing step includes: a mask forming step of forming a mask film on an upper surface of a region of the polycrystal silicon film, the region corresponding to the pressure generating chamber portion in the passage-forming substrate; a boron imparting step of imparting boron to approximately the entire surface of the upper surface of the polycrystal silicon film; and a mask removing step of removing the mask film.
In the sixty-second aspect, boron can be diffused relatively readily in a specified region.
A sixty-third aspect of the method of manufacturing an ink-jet recording head of the present invention according to any one of the fifty-ninth to sixty-second aspects is characterized by further comprising a reservoir forming step of forming a reservoir reaching the pressure generating chamber from the other side surface of the passage-forming substrate.
In the sixty-third aspect, the reservoir can be formed relatively readily with good accuracy.
A sixty-fourth aspect of the method of manufacturing an ink-jet recording head of the present invention according to the sixty-third aspect is characterized in that the passage-forming substrate is entirely constituted of single crystal silicon, and the reservoir forming step includes: a third depositing step of forming a protective film on the other side surface of the passage-forming substrate; a hole forming step of removing a region of the protective film, which corresponds to a reservoir forming portion in the passage-forming substrate, to form an etching hole; and a reservoir etching step of removing the reservoir forming portion reaching the pressure generating chamber from the other side surface of the passage-forming substrate by anisotropic wet etching from the etching hole.
In the sixty-fourth aspect, the reservoir can be formed in the passage-forming substrate consisting of single crystal silicon relatively readily and surely.
A sixty-fifth aspect of the method of manufacturing the ink-jet recording head of the present invention according to the sixty-fourth aspect is characterized in that the passage-forming substrate is an SOI substrate in which the other side surface is constituted of single crystal silicon and the center portion is constituted of an insulating layer, the pressure generating chamber forming step forms the pressure generating chamber so that a bottom portion of the pressure generating chamber can be regulated by the insulating layer, and the reservoir forming step includes: a third depositing step of forming a protective film on the other side surface of the passage-forming substrate; a hole forming step of removing a region of the protective film, which corresponds to a reservoir forming portion in the passage-forming substrate, to form an etching hole; a reservoir etching step of removing a first reservoir forming portion reaching the insulating layer from the other side surface of the passage-forming substrate by anisotropic wet etching from the etching hole; and an insulating layer removing step of removing a part of the insulating layer to form a second reservoir forming portion allowing the pressure generating chamber and the first reservoir forming portion to communicate with each other.
In the sixty-fifth aspect, the reservoir can be formed in the passage-forming substrate consisting of the SOI substrate relatively readily and surely.
A sixty-sixth aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the sixty-fourth and sixty-fifth aspects is characterized in that the protective film is selected from a group consisting of silicon nitride, silicon dioxide and zirconium oxide.
In the sixty-sixth aspect, the protective film is formed of a specified material, thus the reservoir can be surely formed with the protective film as a mask.
A sixty-seventh aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the sixty-third to sixty-sixth aspects is characterized in that the pressure generating chamber forming step and the reservoir etching step are simultaneously executed.
In the sixty-seventh aspect, the manufacturing process is simplified, and the manufacturing cost can be reduced.
A sixty-eighth aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the fifty-ninth to sixty-seventh aspects is characterized by further comprising the protective film forming step of forming a protective film protecting the piezoelectric element after the step of forming the piezoelectric element.
In the sixty-eighth aspect, destruction of the piezoelectric element due to etching is prevented.
A sixty-ninth aspect of the method of manufacturing the ink-jet recording head of the present invention according to the sixty-eighth aspect is characterized in that a hole forming step is constituted for removing the other part of a region of an elastic film and the protective film, which corresponds to the pressure generating chamber forming portion in the passage-forming substrate.
In the sixty-ninth aspect, the etching hole can be surely formed without destroying the piezoelectric element.
A seventieth aspect of the method of manufacturing an ink-jet recording head of the present invention according to the fifty-ninth aspect is characterized in that the passage-forming substrate consists of a single crystal silicon substrate of crystal plane orientation (100), the step of forming the space portion includes the step of forming a groove portion having a width narrower than the pressure generating chamber in the region of the passage-forming substrate where the pressure generating chamber is formed, and the step of forming the pressure generating chamber includes: the step of patterning the vibration plate to form a communicating hole communicating with the groove portion in a region respectively facing the groove portion; and the step of forming the pressure generating chamber in an approximately triangular shape in a cross section by performing anisotropic etching for the passage-forming substrate via the communicating hole.
In the seventieth aspect, the pressure generating chambers can be formed relatively readily with good accuracy and high density.
A seventy-first aspect of the method of manufacturing the ink-jet recording head of the present invention according to the seventieth aspect is characterized in that the groove portion is formed to have a depth shallower than that of the pressure generating chamber.
In the seventy-first aspect, the pressure generating chamber can be formed by anisotropic etching readily with high accuracy.
A seventy-second aspect of the method of manufacturing the ink-jet recording head of the present invention according to the fifty-ninth aspect is characterized in that the step of forming a space portion includes: a first etching step of etching a part of the surface of the passage-forming substrate so as to leave a plurality of columnar portions; and a transforming and flattening step of transforming the chemical property of the plurality of columnar portions and flattening a part of the surface, and the step of forming a pressure generating chamber includes: a hole forming step of removing the other part of the region of the vibration plate, which corresponds to the pressure generating chamber forming portion in the passage-forming substrate, to form an etching hole; and a second etching step of etching the plurality of columnar portions having a chemical property transformed by anisotropic wet etching from the etching hole to form the pressure generating chamber.
In the seventy-second aspect, since it is not necessary to newly deposit a sacrificial layer, the manufacturing time is significantly shortened.
A seventy-third aspect of the method of manufacturing an ink-jet recording head of the present invention according to the seventy-second aspect is characterized in that the transforming and flattening step includes a thermally oxidizing step of thermally oxidizing the plurality of columnar portions.
In the seventy-third aspect, the columnar portions can be flattened readily and surely by thermally oxidizing the columnar portions.
A seventy-fourth aspect of the method of manufacturing an ink-jet recording head of the present invention according to the seventy-third aspect is characterized in that the transforming and flattening step includes a sacrificial layer filling step of filling spaces of the plurality of columnar portions with the sacrificial layer.
In the seventy-fourth aspect, the columnar portions can be readily flattened by the sacrificial layer.
A seventy-fifth aspect of the method of manufacturing an ink-jet recording head of the present invention according to any one of the seventy-second to seventy-fourth aspects is characterized in that the plurality of columnar portions are formed to be arranged approximately uniformly on a part of the surface.
In the seventy-fifth aspect, the columnar portions can be surely removed by etching.
A seventy-sixth aspect of the method of manufacturing an ink-jet recording head of the present invention according to any one of the seventy-second to seventy-fifth aspects is characterized in that each of the plurality of columnar portions has a sectional area of a surface side thereof, which is larger than that of the bottom portion side thereof.
In the seventy-sixth aspect, the columnar portions can be flattened relatively readily and can be surely removed by etching.
A seventy-seventh aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the seventy-second to seventy-sixth aspects is characterized in that the shape of the pressure generating chamber is approximately hexagonal.
In the seventy-seventh aspect, the pressure generating chamber can be formed relatively readily with high accuracy by etching.
A seventy-eighth aspect of the present invention is a method of manufacturing an ink-jet recording head, which comprises: a passage-forming substrate consisting of a single crystal silicon substrate of crystal plane orientation (100), in which a pressure generating chamber communicating with a nozzle orifice ejecting ink is defined; and a piezoelectric element consisting of a lower electrode film, a piezoelectric layer and an upper electrode film, the piezoelectric element being provided on one surface of the passage-forming substrate via a vibration plate, the method of manufacturing an ink-jet recording head characterized by comprising the steps of: forming a polycrystal silicon film on a surface of the passage-forming substrate of (100) plane orientation, which includes the surface and a back surface; diffusing boron in the vicinity of inner surfaces of the polycrystal silicon film and the single crystal silicon substrate excluding the region that will be the pressure generating chamber; forming a first film on the polycrystal silicon film; forming an etching hole in the first film for supplying an etching liquid to the portion where the pressure generating chamber is formed; supplying an etching liquid to the portion where the pressure generating chamber is formed via the etching hole, and the surface of the single crystal silicon substrate is etched by anisotropic wet etching by means of a pattern of an undoped portion of the polycrystal silicon film etched by isotropic wet etching by use of the etching liquid; and forming a second film on the first film to close the etching hole.
In the seventy-eighth aspect, the manufacturing process can be simplified, and the pressure generating chamber can be formed with good accuracy.
A seventy-ninth aspect of the present invention is a method of manufacturing an ink-jet recording head, which comprises: a passage-forming substrate consisting of a single crystal silicon substrate of crystal face orientation (100), in which a pressure generating chamber communicating with a nozzle orifice ejecting ink is defined; and a piezoelectric element consisting of a lower electrode film, a piezoelectric layer and an upper electrode film, the piezoelectric element being provided on one surface of the passage-forming substrate via a vibration plate, the method of manufacturing an ink-jet recording head characterized by comprising the steps of: forming a polycrystal silicon film on a surface of the passage-forming substrate of (100) plane orientation, which includes the surface and a back surface; removing the polycrystal silicon film excluding the region that will be the pressure generating chamber to form a polycrystal silicon film of a specified pattern; forming a first film on the polycrystal silicon film of a specified pattern and on the surface of the single crystal silicon substrate; forming an etching hole for supplying an etching liquid to a portion where the pressure generating chamber is formed in the first film; supplying the etching liquid to the portion where the pressure generating chamber is formed via the etching hole, and the surface of the single crystal silicon substrate is etched by anisotropic wet etching by means of the specified pattern of the polycrystal silicon film etched by isotropic wet etching by use of the etching liquid; and forming a second film on the first film to close the etching hole.
In the seventy-ninth aspect, the manufacturing process can be simplified, and the pressure generating chamber can be formed with good accuracy.
An eightieth aspect of the present invention is a method of manufacturing an ink-jet recording head, which comprises: a passage-forming substrate consisting of a single crystal silicon substrate of crystal face orientation (100), in which a pressure generating chamber communicating with a nozzle orifice ejecting ink is defined; and a piezoelectric element consisting of a lower electrode film, a piezoelectric layer and an upper electrode film, the piezoelectric element being provided on one surface of the passage-forming substrate via a vibration plate, the method of manufacturing an ink-jet recording head characterized by comprising the steps of: forming a protective layer on a surface of the passage-forming substrate of (100) plane orientation, which includes the surface and a back surface, and forming an opening portion in a region of the protective layer, which will be the pressure generating chamber; forming a sacrificial layer on this protective layer and patterning the sacrificial layer to leave at least the region covering the opening portion as a remaining portion; forming a first film on this sacrificial layer; forming an etching hole communicating with a peripheral portion of the sacrificial layer formed on the protective layer; supplying an etching liquid via the etching hole to remove the sacrificial layer, and performing anisotropic etching for the passage-forming substrate from the surface side by the specified pattern of the protective layer to form the pressure generating chamber; and forming a second film on the first film to close the etching hole.
In the eightieth aspect, the manufacturing process can be simplified, and the pressure generating chamber can be formed with good accuracy.
An eighty-first aspect of the method of manufacturing the ink-jet recording head of the present invention according to the eightieth aspect is characterized in that, in the step of patterning the sacrificial layer, a groove portion is formed across a periphery of the opening portion of the protective layer.
In the eighty-first aspect, the manufacturing process can be simplified, and the pressure generating chamber can be formed with good accuracy.
An eighty-second aspect of the method of manufacturing the ink-jet recording head of the present invention according to any one of the seventy-eighth to eighty-first aspects is characterized in that the pressure generating chamber is formed in an elongate shape, and the etching hole consists of a slit formed along a longitudinal direction of the pressure generating chamber.
In the eighty-second aspect, since the etching hole consists of the slit, the passage-forming substrate can be surely etched via the etching hole, and the pressure generating chamber can be formed readily with good accuracy.
An eighty-third aspect of the method of manufacturing an ink-jet recording head of the present invention according to any one of the seventy-sixth to seventy-ninth aspects is characterized in that the etching hole consists of a plurality of pores formed at a specified interval.
In the eighty-third aspect, since the etching hole consists of a plurality of pores, the passage-forming substrate can be surely etched via the etching hole, and the pressure generating chamber can be formed readily with good accuracy.
An eighty-fourth aspect of the present invention is a method of manufacturing an ink-jet recording head, in which a pressure generating chamber is formed on a passage-forming substrate, and a piezoelectric element consisting of a lower electrode, a piezoelectric layer and an upper electrode is formed on one surface of the passage-forming substrate via a vibration plate, the method of manufacturing an ink-jet recording head characterized by comprising the steps of: forming the passage-forming substrate having a silicon layer consisting of a single crystal silicon substrate on each of both surfaces of a polysilicon layer to which etching selectivity is imparted by doping boron in a region other than that having the pressure generating chamber formed therein; laminating sequentially the lower electrode, the piezoelectric layer and the upper electrode on one silicon layer side of the passage-forming substrate via the vibration plate and patterning the same to form the piezoelectric element; etching the other silicon layer of the passage-forming substrate to reach the polysilicon layer, thus forming an ink introducing port, patterning the polysilicon layer in the region that will be the pressure generating chamber via the ink introducing port, and etching the one silicon layer with the polysilicon layer as a mask, to form the pressure generating chamber.
In the eighty-fourth aspect, the passage-forming substrate is selectively etched via the ink introducing port, thus making it possible to form the pressure generating chamber relatively readily. In addition, since the pressure generating chamber and the like can be formed by etching the passage-forming substrate from the surface opposite that having the piezoelectric element, protectability for the piezoelectric layer is improved, and operational efficiency is improved.
An eighty-fifth aspect of the method of manufacturing an ink-jet recording head of the present invention according to the eighty-fourth aspect is characterized in that the step of forming the passage-forming substrate includes a step of doping boron on a surface of the other silicon layer joining the polysilicon layer, which is at least a surface layer of the region facing the pressure generating chamber.
In the eighty-fifth aspect, when one silicon layer is etched via the ink introducing port, the other silicon layer is not etched, thus the pressure generating chamber can be formed relatively readily.